Ian Rankin's book "Doors Open" starts in an auction room, and that was where I started my exploration of buildings in Edinburgh's Doors Open weekend: Lyon & Turnbull. Their auction- and showroom is housed in an imposing Georgian former church not far from me: it is at the end of a short street, the building's columns drawing one down the road.

It was quite interesting inside, though adaptations for its current use means that its previous functions is somewhat obscured. I didn't take any photographs inside, for instance - though I did see some chairs that I went back and bid for the following week.

I also went to the very similar, still-functioning church opposite my flat. Though they weren't in the Open Doors official list, they had decided to open their doors anyway. It was a very similar design to the now-auction house, and interesting to see it in use. The congregation was once measured in thousands - the church was built by statute to accommodate the families of the expanding New Town: for every so many new dwellings, the council required that there were so many churches, too. Now, it is probably measured in tens (although there are always lots of cars parked in the street on Sunday mornings - though that may be due to the evangelical chapel down the road, too).

I then headed west, via the James Clerk Maxwell Institute - in a rather fine four storey New Town house, where JCM was born (and without whom much of the modern world might not be possible - unless someone else had come along to make his discoveries in his place) - to two fascinating buildings in the west end. First was the Drumsheugh Baths, a Victorian swimming pool designed in a Turkish style with all sorts of strange poolside equipment - swings and trapezes instead of diving boards (and, since it is a functioning swimming pool in use, they ban photography). The second was Lynedoch House, home to the Edinburgh Society of Musicians, a building I have been in before - indeed, I played there several years ago. It is a bit of a warren, with a large room overlooking Dean Village and the Water of Leith. They had someone playing short piano pieces; I sat staring out of the window at the amazing view, listening to some lovely piano playing. It felt rather special.

I walked back along the Water of Leith, and popped into St Bernard's Well. I have been past many times, but never inside the well itself. It is a beautiful building, tiled in mosaic. The pump still works, but the council won't let you drink the water - 'elf and safety...

The following day I went to more temples: curiosuly for the centre of the Enlightenment, Edinburgh has a large variety of faiths and places for them to worship. I first went to the (former) Glasite Meeting House. I had never heard of Glasites before. They have a history that could have been written by Iain Banks. The last Glasite elder died in 1999. It was a plain building, now used for meetings and events. It had a remarkable glass ceiling boss, the only source of natural light into the meeting room itself. Presumably to stop the congregation being overly distracted - the guide explained that their pews were especially spacious because worship in one form or another went on for hours.

Around the corner from the Glasite meeting house is the Edinburgh Baha'i centre. In a beautiful Georgian townhouse, a small congregation meet. It was a beautifully restored building, and a fitting end to Open Doors.

It was about "Patterns in Nature", though it was more about how we use nature's patterns to create non-natural forms in art and engineering. As Neil Cooper, the chair, said, humans are pattern recognising creatures, and pattern is fundamental to the way we interpret the world. (Indeed, we are so good at recognising patterns that we see them when they are not really there...)

I had seen Randall-Page's work, though I hadn't recognised his name before he showed some examples of his work. His biomorphic shapes, based on Fibonacci spirals but cut into naturally occurring rocks, and hence imperfect, reflect the shapes found in pine cones and the heads of sunflowers (and many other plant forms). He described the spiral pattern as efficient - the optimal way to organise plant structures.He views the spiral as the theme, and the imperfections as variations on a theme - indeed, much of what he said sounded like improvisation around the theme, with a tension between the randomness of the imperfections and repetitive pattern.

Alistair Elfick is an engineer who works in "synthetic biological engineering". He was quite critical of engineers, believing that they had forgotten how to play, being constrained by professional standards and an avoidance of failure. It has to be said, though, that for most engineers, an avoidance of failure is a good thing - I'm not sure I'd want to cross the bridge built by an engineer who was happy playing - and failing...

For Elfick, bioengineering and "synthetic aesthetics" involves biomimicry - learning (and stealing!) from the natural world. The user of synthetic materials, he felt, created a whole new taxonomy - a new branch to the tree of life: the ability to develop synthetic biology. (He pointed out that much of this ability is based on our use of organic chemistry to make and manipulate synthetic, organic compounds; many of which our derived from or based on compounds made by organisms long ago in the earth's history. Not so novel, then!)

Like Randall-Page, the patterns discussed by Elfick are based on simple models: chemical diffusion and reaction can create complex, chaotic patterns using very simple formulae.

The debate after their presentations came up with some interesting topics. Many interesting things happen at the edges - the liminal is an interesting place to be. But the scientific method is reductive in its approach - it is linear. Science works on the differences between things, not the connections that can be made.

Man, however, is a pattern recognising creature: we look for meaning in things, including art, science - and religion! Ancient people looked at the night sky and joined the dots, turning the stars into pictures and giving the constellations names. We look at clouds and can see pictures in them. Music is attractive because of the patterns we hear (and exciting because of the surprise when the unexpected happens!).

For all the examples they used, I've occurred to me that something went unmentioned. Man has been stealing fron nature's patterns for a long, long time: it isn't new. The roof of the large, newly renovated Victorian main hall of the museum resembles nothing so much as a vertebrate ribcage from their collection!

I had plenty of time to get from Paddington to Kings Cross for my train back to Edinburgh, so I did something most Londoners wouldn't dream of, and walked. (It wasn't the first time - eighteen months ago, I walked from St Pancras to Paddington one frosty December evening, when I needed the exercise and air. Even then it felt unusual; and I still reached the pub before my friends.)

It was sunny and warm - pulling my case behind me, I broke into a sweat. Between Paddington and Great Portland Street, I stayed off the main roads, going down streets I have probably never walked down - Marylebone isn't really my part of town.

I went onto Euston Road to explore Regent's Place and Triton Square - mostly for the Gormley sculture, "Reflection".

Once I got there, I was impressed by Greenwich. I went often as a child, but only once in adult memory, a couple a years ago when I was exploring Canary Wharf and took the tunnel under the Thames; I didn't really look around much.

This time, Cutty Sark was back, and I looked around many of the grand Wren-designs on the way to the Royal Maritime Museum, where the Ansel Adams show was on. (When we were children, my brother and I spent many afternoons looking at the large model boats they have - or at least, I had - I didn't look much around the museum, though I was impressed with its architecture, both classical and modern.)

The painted hall and the chapel were stunning.

As I was leaving to find the station, I saw the start of a beautiful sunset. So I stayed on, wandering around, looking at the effect of the sky on the buildings.

I was in London last month, and I took a trip along the Thames. I hadn't intended to; I wanted to go to the Hayward's "Light Show", but couldn't face the queue, so I walked to Tate Modern, which was full of school children and the members' room was so busy they were queueing out of the door.

I decided instead to go to Greenwich to see an exhibition of Ansel Adams' photographs - one of my favourite photographers.

It was a great exhibition - lots of high contrast black and white prints - but best of all was the fast boat ride I took from Bankside to Greenwich.

Since today is St Andrew's Day, here are some photos of the Scott Monument (Scott being the man who invented the image of Scotland popular around the world...) as well as some other pictures taken last month...

I love Tate Modern, on Bankside. The view across to St Paul's Cathedral and the City is amazing, but the building itself - a former power station designed by Gilbert Scott - has an austere, industrial beauty.